Light emitting diodes (LED) have been popular in electronic device applications, for instance, indicator applications, displays of laboratory instruments, and illumination applications. An LED string, which includes a plurality of LEDs connected to each other, utilizes a current flowing thorough the LEDs for operation.
When a Direct Alternating Current Drive (DACD) LED system including the LED string is being supplied with a continuous AC voltage, a Power Factor (PF) of the DACD LED system may be maintained near one (i.e., 1) by having an instantaneous current through the DACD LED system be proportional to an instantaneous level of the continuous AC voltage.
When the DACD LED system operates in a phase cut dimming mode, such as when the DACD LED system is supplied with a discontinuous AC voltage by a triac-based dimmer, a waveform of a current flowing through the LEDs may transition abruptly from being proportional to the instantaneous level of the continuous AC voltage to having a fixed value when the current is not zero. Such an abrupt change in the waveform of the current flowing through the LEDs may produce a flickering of the light emitted from the LEDs.